Hi and welcome. You may not get much of a reply at the moment, as GS members are absorbed by the Olympics, but as a quick first response: Used skates are not recommended at any level and particularly not for beginners. They have probably been moulded for their previous owners and then further shaped by the warmth of their feet. More moulding might help a bit, but probably not enough to prevent pain and problems like blisters that will not make learning to skate fun for you. Also you don't know how much life is left in them and they'll more likely than not break down quickly, which will be dangerous for you. Skating is a sport prone to injuries, especially with weak equipment.
An adult with your specs needs stronger, stiffer skates than a child beginner. The Riedell Stride is stronger than the brand's recreational skates, but a broken-down used pair may not have the stiffness left that you need. The other question is whether Riedell is the right brand for your particular feet. Different brands of skate boots are designed for different shapes of feet (toe angles, arch height, anklebone prominence, etc). Where do you live, and someone here can recommend the best skate shop and fitter near you? The cost of good skate boots and appropriate blades is high, but skating injuries are common and can be life-altering. Having the best equipment is vital, for your enjoyment and your safety. Good luck!