Cellar - tanking slurry issues

[Andrew Q]

I’ve recently (a week ago) tried tanking my cellar walls with KA tanking slurry. This seemed to go on quite well, but the lower half of the wall (section below ground) has now become discoloured and is covered with droplets of water. I’m hopeful this is condensation, but I’m concerned the tanking has not worked. A builder did suggest a fan to improve ventilation once I had done the tanking, the cellar lacks ventilation and I am considering a fan out through the circular hole which is currently just a vent. There is also a section of the cellar that I have not yet tanked, it has a bricked up coal chute. That might assist ventilation??

Any suggestions about the tanking and fan would be welcome (humidistat? Regular?). My DIY skills are not good!

Thanks in advance,
Andrew