Welcome to the wonderful world of Python, where specific versions are only supported for a couple of years before programmers are expected to update all the code they’ve ever written to run in a newer language version.
However, the good news is that Python 3.7 isn’t dead yet (it’s supported until 2023), and I believe Anaconda still support it too.
It’s just that the Anaconda website is entirely unhelpful. If you download the current installer — the one Anaconda tell you is Python 3.8 — and then you follow the completely incomprehensible instructions here: <https://conda.io/projects/conda/en/latest/user-guide/concepts/environments.html> then you can use it to create a Python 3.7 installation.
In case you are not a fluent speaker of gobbledygook, and need somebody to translate the Anaconda website into English for you… there’s a StackOverflow thread here where somebody has asked a question very similar to yours, and the comments explain exactly what commands you need to type to get a Python 3.7 installation… https://stackoverflow.com/questions/42978349/anaconda-version-with-python-3-5