Q.Why After Three Years Has My Climbing Rose Not Flowered
The foliage is excellent but no buds or flowers

Certified GKH Gardening Expert
If this isn't fed, frequently, then this is likely the issue.
Roses are heavy feeders, and will require feeding quite often.
Here are some articles that will help:
https://www.gardeningknowhow.com/ornamental/flowers/roses/rose-fertilizer.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-moisture-in-plants.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-ph-plants.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/making-sure-soil-drains-well.htm