Apps that runs on the NAS? See section Packages https://www.synology.com/en-global...

The app selection is limited because this NAS has only 512 MB of RAM, not many applications will run, a bit of Media Playback, limited by the RAM, the performance would be super slow. These NAS types are maybe suitable as entry level for backup purposes, but you would not be happy with the performance. This is one of the reasons why so many such j-models are available for cheap as used devices. A lot of people probably bought these and then realized, hey they are not very powerful and had to sell them and buy a new one.

I advise only in buying a 4 bay NAS, you have more RAM, better CPU options and expandability. Plus with a 4 bay NAS you could also use smaller size disks and you still would achieve a good capacity (e.g. buy 4 x 2 TB and your NAS would have a 6TB RAID5 capable storage solution, if you want to achieve the same with a 2 bay NAS you need to buy 2 x 6TB and if one disk fails, you need to buy another 6TB drive, if one disk in a 4 bay NAS with 4 x 2 TB drives fails, you only have to buy a 2TB drive for restoring redundancy plus you could also install a bitter one at the time prices drop later and expand the capacity even further).