Somewhere on the forum I thought was a guide, by Roger, alias grumpy grandad? From memory of how we used to fit ours, a short version is :-
1 - slide the main fabric into the awning track [a short single caravan step will be of use] and then throw it all up onto the roof out of the way. It will want to slide back down but you should manage it.
2 - lay poles out on the floor and assemble the front frame, but kneeling the front frame legs
3 - assemble roof poles and hook the end two into the lugs on the awning rail, twisting the other ends into the kneeling front frame that your 16 year old son is holding. It will wobble around so do not shout at him.
4 - hopefully the hooks have not fallen out of the lugs and you can now juggle the roof frame into place un-hooking each end in turn to feed through the off white end plastic fitting. This bit is fiddly but worth persistence.
5 - fit the short vertical pole that sits mid way along the awning track.
6 - drag the fabric over the kneeling frame and lightly tension the poles to take up some of the slack. Centre the awning up with the van if needed.
7 - fit the centre ridge roof pole.
8 - fit the short projection poles that hold up the fringe at the front of the awning.
9 - extend the front legs from kneeling position.
10 - fit fabric side panels and front, re tension poles slightly.
11 - peg out, 4 corners first, but do not drive pegs home firmly as you will usually need to take a couple out and adjust.
12 - make any adjustments you need to, fit skirt if it is cold but leave out if weather is hot.
13 - lay breathable groundsheet if using one.
14 - if weather is good do not remove panels, just unzip the sides and roll down into a sausage.This means if it turns or when night time comes you can quickly enclose the awning without faffing around and having to re-peg. It will also keep the awning in shape.
It will probably take you 45 minutes first time, but you will half this with practice and find it possible to put the awning up using the front pole and roof rafter instead of the front frame and end rafters

When you come to pack away we found it easiest to remove panels which we cleaned and packed.
You will be able to wipe down the bottom of the awning sides with a damp cloth and wrap the front bits up off the ground so they can dry off.

Alternatively you could sell the awning for £100 ish and buy a Vango Siesta or Elwood, such as this https://www.gumtree.com/p/campervan-cara...ood-/1428577455
I did a review here Vango Siesta Review [Elwood is the same but in blue]

Best of luck - Colin

Any good? g181-Soplair-Awning-assembly-instructions.html

These chalet type awnings are not as popular as they used to be but they are of good, strong design and once you get used to them they are just as easy as the more modern ones. With all awnings, it's the pegging down that takes the time.
Don't forget that the sides and front zip out so initially, erect the awning and poles without the sides and front. That'll reduce the weight.

Once you've got the framework and the roof canvas on, THEN zip in the sides and front BEFORE finally tension the poles and pegging down.

Randa

Also, it's a good idea to mark the ends of the poles and fittings with different coloured insulating tape to indicate what fits where. This can save a lot of time when laying out the poles etc prior to assembly.

The 290 will be to short. You do need the 340. I have one of these but only use it for long pitches when I know I'm staying put for a a couple of weeks or longer. The Vango Siesta. we own is a little smaller but a lot quicker and easier to get up. It does not fit as well but I do like it and for 90% of the time it really is a very good option.
I think if/when we move up to a larger Eriba we would not go for a full size awning and the Vango would be large enough.

Colin