Q.Rubber plant
I recently purchased a very large rubber plant from a woman who has been growing it for over 12 years. I’ve had bad luck with them in the past but since she did so great with this one and I was following her directions to a t I figured I could do well with this one. I was wrong and I need help. All the leaves are turning yellow and falling off and I’ve watered it exactly like she said and it in a large window getting indirect sunlight. I’ve had it just over 2 months and it started about 3 weeks after I got it and it’s just getting worse. This is a 10ft+ tree and it would break my heart if I killed it. I don’t know what to do. Please help!

Yellowing leaves are likely an indication of a watering issue; too much or too little.
It's best to check the soil instead of watering on a schedule. The needs of the plant likely changed in a new environment.
These links will help you.
https://www.gardeningknowhow.com/houseplants/rubber-tree/watering-a-rubber-plant.htm
https://www.gardeningknowhow.com/houseplants/rubber-tree/how-to-care-for-a-rubber-tree-plant.htm