Hi @anipar ,

Unity Catalog requires workspace on Premium plan or above. Check if you've created workspace with required tier. Another thing that is possible - your workspace hasn't been automatically assigned to metastore. 

If so, you need to follow below steps:

1. Go to your workspace 

2. On the upper right corner click your workspace name

3. Click manage account

4. Your account console should open

5. Click catalog and then click on your metastore. If you don't see any metastore you can create new one by clicking "Create metastore"

6. Once you select/create metastore you will be able to assing workspace to metastore by clicking "Assign to workspace" button