There may be a few reasons why you do not see / do not have access to Custom Tables in the Contacts dashboard of your account. (To find navigate to Contacts > Configuration > Custom Tables).
1. You do not have the permissions set for your administrator record to access this feature.
2. Your account is not on an Enterprise license.
3. Your custom table was created prior to July 16, 2018.
4. Your custom table required development work and therefore is not accessible in the user interface.