I tiled my swimming pool in 2017. It still looks just as good now as it did then. I followed a guideline on the TAL website:
1. Ensure that the base is clean and properly cured.
2. Mix TAL key coat with 42 mpa cement (no sand, no water), to make a slurry. Paint this onto the surface with a block brush, ensuring full coverage. Do not mix too much, as the working time is only about 15 minutes.
Allow to dry for at least 4 hours.
3. Use TAL Goldstar 12 tile cement, mixed with TAL bonding liquid (no water!) to bed the tiles.
4. I used TAL acid-resist grout, due to the chemicals in a pool. I'm sure that in the shower, any grout can be used. Once again, use only bonding liquid to mix. Don't wait too long to clean off the tiles after grouting, as this sets hard and grips like you can't believe.
If it works for a pool, I'm sure that a shower environment would last using this process.