Link for client to view model

how to get a link for my client to view model, he has free version I have pro. thanks

Which free version?

If you want him to be able to view it but not edit it you could publish the model to Trimble Connect. Then go to connect.trimble.com, sign in and go to the folder in which you saved the file. Select its tick box and then click the Share button on the right side.
Screenshot - 11_8_2021 , 8_00_34 AM

They can follow the link and open it in the online Viewer.

If you want to give them total access to the file, including editing capabilities, you can upload the file to Trimble Connect or DropBox or Google Drive and send them a link to download. Which one you use depends on which free version of SketchUp they are using.