Why can' I create new instances

Summary:

I am using a free account (free trial is over, but I am supposed to have access to always free services, as the banner suggests).

I have only one instance Ampere 1 core 6 GB, so I am far from the limit here.

I had other instances that I terminated and they doesn't appear on my instances list.

I can't create anymore instances.

Content (required):

When I try to create new instances, I have the following error: You cannot create a volume because you have reached your limit. Upgrade to a paid account.

As said in the summary section, I am not at the limit and if I navigate to the limits and quotas, it is listed 3 cores and 18 Gb available.