It’s quite easy to do yourself.
Select a friends episode as normal with TG in manual mode (can even be one you have one already as you wont be saving it).
Once it prepares the sheet for you. Go to bottom right box called Moviesheet editor and select the movie thumb.
If you go over to the far left under search results, choose a picture you want (a generic one for a folder full of seasons)
Click the green tick under the cover window, this will move the picture inside the frame at the bottom right.
Then click the blue disk in the bottom right window “save original moviesheet to disk somewhere”. Save it as folder.jpg and boom you have a nice folder thumb.
What I do is select episode 1 of Season 1 and create a Season 1 folder.jpg, select episode 1 of Season 2 to create a Season 2. jpg and so on for the actual Season folder.jpgs.
