Hi Aishwarya,
There is currently an issue with the sandbox for that module which is why it just shows 99% or some sort of error with retry button.
To work around the issue, please open a new browser tab and navigate to below link:
Solve puzzle(s), review/accept permissions, etc., and wait for window on right side to show Welcome to Azure Cloud Shell. Next leave that tab open, and click on the exercise browser tab you were on and complete the instructions.
I just tested and was able to follow the instructions in the exercise without any issue using above workaround. Even though it isn't part of exercise, I went ahead and created a virtual machine as well.
Please give workaround a try and let me know your results.
Please click Accept Answer and upvote if the above was helpful.
Thanks.
-TP