The only way to export or convert .abk files, is to actually recover them first with Ability Write, which is the only software that can recover these document backup files. As for export to .asc files, this can actually represent export to any kind of text file, including ASCII encoded. So abk to asc conversion is not possible directly, but once you recover the documents you can export them freely. The main issue will be to find someone with Ability Write or try free trial version and hope for the best.
Updated: August 21, 2023