I saw other people complain on Twitter, but it happened to me also. I am 100% sure I had this plugin installed before, but now when I try it says “Plugin not found”.
What I found out: On my work computer where I’m logged in with different account I can see and install the plugin, so it’s not geo location problem as I saw somewhere on Twitter.
I had people contact me about the same issue. For me it was because I had set minimum version of XD to 21 and they were still using XD 18 so it didn’t show up. When they upgraded XD the plugin showed for them (also some said they needed to do a restart).
There is also a max version property in the manifest so that a plugin only will show up in a specific range of versions.