hello @maxjolt try on 'check for updates' use the left mouse button you see then one signe (more) use it.
after this operation clic on the card and ask manually to download.
can you also for precision give the number of shows you have buy please ?
i post here one picture of your collection.
for your question and what can append, alway buy one time, no clic two time for one show leave the window buy open all time you not see activity stoped. in general when we use buy the procedure are made. for know if the site have problem, just you see when you try to open one windows and that ask a long time, then in this condition not buy, wait generaly the next day.
the week end are again a critical situation, because internet have lot users and players, here if you see a slow situation wait monday.
for test you open several sujet and if the sujet are open without problem, you can buy.
always buy one show by one show, control the show are in your collection and eventually download and then get the next show.