Error message when calling ./build.sh, ./test.sh, or ./export.sh

In the algorithm tutorial, I get an error message when calling ./export.sh :

./export.sh: line 3: ./build.sh: Permission denied

I get a similar message when calling ./test.sh or ./build.sh. I'm using Ubuntu 20.04 on WSL2.

Also, I'm pretty new to Linux, so I'm not entirely sure this is the right place to ask.

I found that the bash script lacks execute permission. This is solved by running:

chmod u+r+x build.sh

or running the bash script with sudo bash in front.