Okay, it is a backup file. Unfortunately it has been created with Adabas Version 3.3.4. which is out of support for years, see also ADABCK ILLLOG - Forum - Adabas & Natural - Software AG Tech Community & Forums.
Since you are trying to do a cross-platform backup/restore from a big-endian (Solaris) to a little-endian machine (Docker Linux) you need to have a backup file at least from Adabas version 6.3.
In principle you need to upgrade your backup/database on your Solaris machine until you reach at least Adabas version 6.3. using the adacvt Adabas utility.
From this point you should be able to do a cross-platform backup/restore from your big-endian Solaris machine and restore it on any other little-endian platform.
Reach out for your Software AG support team. I guess they can help you taking the steps necessary to restore your data in one of the latest Adabas versions and run it in docker, cloud or wherever.