I agree, Motorola file manager is a safe option. If you need more features you could try FX or Total Commander. On my MXP I use Solid.Get rid of it... Motorola file manager, now in the play store. Basic, but works great.
Solid Explorer... I left ES a while back due to the ads and bloat that are not needed in a file manager, they tried to too much and failed, it was once the king of file managers, but sadly no longer. I am not familiar with the Moto File Manager.