To initialize your shell run the below code
source ~/anaconda3/etc/profile.d/conda.sh
conda activate Your_env
It's Worked for me, I got the solution from the below link
https://www.codegrepper.com/code-[“CommandNotFoundError: Your shell has not been properly configured to use 'conda activate'.][1]examples/shell/CommandNotFoundError%3A+Your+shell+has+not+been+properly+configured+to+use+%27conda+activate%27.+To+initialize+your+shell%2C+run