INSTALL process is not correctly explained...

[mtregael]

If the roundcube database has a prefix, it must be user in the sql statement.

You said in INSTALL file:

2. Execute the relevant SQL/.initial.sql script on your database (process depends on your DB engine)
   If your Roundcube Database starts with a prefix set the prefix also in the SQL Statement: "REFERENCES PREFIX_users(user_id)"

but it should be:

2. Execute the relevant SQL/.initial.sql script on your database (process depends on your DB engine)
   If your Roundcube Database starts with a prefix set the prefix also in the SQL Statement:
   "CREATE TABLE PREFIX_collected_contacts ("
   and
   "REFERENCES PREFIX_users(user_id)"

[Programmierus]

@mtregael thanks for this :)