Need help on Retinol and Glycolic Acid

Firstly whatever scrub you're using - I'd recommend to stop using it. Majority of scrubs can damage your skin by making micro-tears in your skin. In terms of glycolic acid, you should introduce it gradually into your routine - when and how to use it would strongly depend on the actual product you're using. Same goes with retinoid - do not use both together in the same routine - and use it in the PM routine. You can start with a sandwich method (moisturiser-retinoid-moisturiser) to let your skin adjust and prevent any dryness. Otherwise, apply it like a serum, let it dry for a couple of minutes and follow up with a moisturiser. Start with once a week and increase the frequency if your skin is ok and not drying or getting otherwise irritated. You might want to use them both on alternating nights and spf is a must the following day.

If your skin sensitive you can start slowly and test patch to minimum risk and irritation.