The end customer does not use the Allegro tool. They work in an Altium environment. I am not sure there is a way to convert the .brd file to .alg
Altium Designer’s Import wizard includes the capability to import Allegro PCB designs in both binary (.brd) and ASCII (.alg) forms, which are translated to Altium Designer PCB files.
Please follow the below links for more details:
Allegro Import | Online Documentation for Altium Products
Import Wizard | Online Documentation for Altium Products
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