Need more details. How are you sharing if no iCloud? Home sharing?
Is your free iCloud 5GB “full”? I suspect you ARE using
that iCloud space, perhaps without knowing it (else, how are other people seeing other albums) and- if so- maybe you are out of free space to also share the new album? 5GB is not very much space when it comes to Photos libraries... even more so when Mail & Messages, etc are taking bites from that same small pool.
Or if you are home sharing and synching individual albums, you probably
DO have to specifically add the new album to the share album list. And your iPhone and iPad have to be in the same “home share” network to “see” it. If you are synching albums, you have to reschedule to add a new album to your devices.
If you have home sharing set up to sync
all albums automatically, are you perhaps out of sufficient free space on the 2 devices (thus not enough room to share that album too)? If you have to manually sync, have you synced the 2 devices since creating the new album?
Perhaps the other people are the "controllers" of the albums and they have shared them with you in the past? Over time, you may think you are sharing albums with them but they actually control the share. If so, they may have things set up to allow you to add photos to their shared space but not add albums?
Explain how you are sharing other albums now, both to your devices and to the “other people’s” devices and it should be easier to help you.
