Other than telling them how to go to Stock and choose images for themselves there are a couple of other options that may work for you that I have done.
1: Add a selection of images you think would be best to a library and then share that library with them
2: Actually create the project with images you think are best and have them approve it that way.
Personally I have found number 2 the best and most efficient as most times the client will say, 'Yeah, that works good' and you have both saved lots of time.
Thanks for your input
How do you share a link to a Library - When I tried -Adobe wanted a password etc to sign in?
Sign into your account at creative.adobe.com and go to 'Creative Cloud Files'
Select 'Librairies' from the side menu ...
In the drop menu for each library you will see some options to share the Library. Usually the Email or Collaborate options are the one you want to use. Just follow the prompts after making your selection.