Is it ok to take adderall (dextroamphetamine and racemic amphetamine) xr and a preworkout supplement with caffiene and beta alanine in it?

Yes: You are adding a little more stimulant but shouldn't cause a problem

Perhaps (or not): If you are on adderall (dextroamphetamine and racemic amphetamine) daily and have not had any problems you can try the supplement and the most likely side effect will be fast pulse/ increased blood pressure/ feeling of racing/anxiety - if you get no change or other side effects then you can likely tolerate the combination. With any side effects stop the supplement

Caffeine not needed: You might find taking caffeine and Adderall (dextroamphetamine and racemic amphetamine) gives you too much stimulation resulting in a rapid heart rate and elevated blood pressure. If you skip the caffeine you might save yourself from a health risk.