I have created a plugin and linked the primary ACF group to that along with 2 other subsidiary ACF groups
Thats all fine but…
I have 3 existing tables with data that I would like to import to the ACF but I don’t see any such tables in Adminer so where is the data created by ACF kept and can I import existing data to each ACF group please?
ACF field values are stored in post meta, use meta, term meta or options dependent on that the fields are attached to. ACF does not have its own tables.
Are the __fieldname and associated id_1234567 per field entry critical.
ie: would I have to create these for each data entry to mysql the data to this table?
Yes. Each field in ACF has a corresponding field key reference value. Both field are important.