Hi,
I never use the help files but I just tried now and get the same error.
MyHomeSuite files are called plants. Within them are the devices. The one you need is MH202. Right mouse click on it and there should be options for import and export project as well as send and receive configuration. I never do much with project files except to back them up sometimes. It is the config you want. Select receive the config file. This will then be brought into your ‘project’ that is part of the MyHomeSuite .plant file. When you change anything in the config you then send the new config file. I think projects, . prj files, are for when you want to send or receive setups from someone else.
I use several plants to keep file sizes smaller and spread the risk if something went wrong. I have one just for MH202, another for Screen10 and another for all my other devices. You could also just have one with all your devices in the one plant
Manual is here:
MH202 manual
So first step is to create a new plant. Then search using the scanner for the MH202 on your system. When you find it you the drag it over into the main area. Save the plant. Next step is to receive the configuration. Save the plant. Once you have it saved you can then open the config file to view it and make changes. After you have made the changes you want select save and then save the plant. Then send the new confguration to the MH202. You will need the IP address and the password for the MH202.
I keep saving the plant. I am old school and expect crashes 
Also, sometimes MyHomeSuite messes up and sends an empty config files to the MH202 and not the one you just updated. That would be a disaster if you haven’t kept backups.
this thread is by far the best I could find on the web
BTicino used to have their own forum but pushed the end users off and aimed the forum at just dealers. Shame as there were a lot of knowledgeable people there but sometimes I see its not in BTicino’s business interest to encourage some of things we do or would like to do
I then started my own ‘help and knowledge exchange’ type threads over on AV forums as an experiment but I and others didn’t like the forum there. I made a lot of guide like threads but eventually stopped posting there due to lack of support and lack of posters. In the meantime I started using openHAB and after a while I encouraged people landing on my old threads, like the OP searching for info, to start a new thread here as this place seemed to be where there are the biggest number of active end user experts. I had also run out of enthusiasm for initiaiting the ‘Info’ type threads and so here was another experiment to see if I there was enough interest for basic info type threads and if it was even OK to use openHAB forum for this
ps openwebnet works great with openHAB. It can take your automation to a much higher level than just BTicino scenario controllers thanks to the great developers on here and the ability to combine many things into one functioning whole home automation epxerience