So I’m going to throw you a bone and teach you how to start fishing rather than just asking for the fish.
So first what you are doing is identifying the card. Aside from a proxmark, Taginfo is your second most reliable tool for identifying the type of chip. What you are looking at is a 4 byte uid mifare s50 card, possible clone rather than an original manufacturer issued card.
Mifare chips mostly come in flavours of 4 or 7 byte uids and 1kb or 4kb memories. S50 are 1kb memory chips and S70 are 4kb memory chips.
Now without seeing the rest if the sectors, I’m going to assume that they’re not encrypted. The manufacturers signature looks to have been written with a default filler (I could be wrong here) which is why first impressions are that the gym are using a cheap off the shelf writer and possibly using a uid only ident system. This is only confirmed by seeing the rest of the sectors.
And don’t forget the big D. Datasheets. These are good reading material to understand the structures of nfc chip.
Also since you have android phone, a good cheap way of getting into researching nfc tags is to pick up a pn532 reader which should work on the usb otg for your phone.