Marking Up Photos in Lightroom

There is a box on this webpage to instruct you how to change plans. Click on that box and it will tell you everything you need to know:

Adobe customer care 

Photoshop cannot be purchased outright. It is only available by subscription in the creative cloud program. Depending on which subscription program you have signed up to, it may be included. The only Adobe program that can be purchased is Photoshop Elements. I'm not familiar enough with it to know whether it would have enough drawing features for what you need. It sells for just a little over $100, I think.

Photoshop Elements information 

Lightroom is a digital darkroom.  For drawing, use Photoshop CC which has a wide assortment of Brushes, Pencil, Pen, Eraser and Shapes.