We have found one software suitable in our database for this conversion.
The only way to convert .adp files from Microsoft Access to .mdb files which were used in the earlier versions of the very same database program, would be to use some of the later versions of Access that does support .adp files.
When you open your .adp files in MS Access, you can simply use File ► Save as.. function to resave your databases to MDB format, which will essentially achieve adp to mdb conversion for you.
Updated: October 3, 2022
ADP
Files with adp file extension are database projects created in older versions of Microsoft Access. Replaced by .accdb files in later MS Access.
MDB
An mdb file extension is used by Microsoft Access database management system for its main database files. MDB format was replaced in later version of Microsoft Office by ACCDB format. Access mdb databases can usually be opened in or imported to most database management systems, such as dBase, Oracle etc.