E2:If this is somehow the first post you found in your journey, this master list of apps and how to download them will help more than this post:https://lemmy.world/post/907413 Also the test flight links in the post worked.
There are no lemmy-related apps in the iPhone store. All the websites for the apps lead to placeholder websites or websites that don't work.
E: Thank you all for your help. The websites only work when accessed via phone. Still no test flight codes yet. I'm not going to delete this because I know others are probably going to have the same struggle and question.
You should be able to save the weblink to your home screen through Safari.