The structure of your tree tree is more complicated than my code expects. In addition to tips and branch lengths, your file has entries for node names. For example, one bit of the tree file looks like this:
That treats "Belgium/ULG-6216/2020" and "Ireland/Dublin-19072/2020" as two tips, each with a branch length after their respective ":". They are then enclosed in parentheses. What follows "NODE_0000305" appears to be a node label followed by ":" and the subtending branch length. My code is vomiting on the node name because it expects a ":" directly after the closing parenthesis (my code automatically numbers nodes using its own scheme).
You could probably strip out the node names with a search and replace for "NODE*:" to ":" if you have the right tool. Even Word will do it with the right wildcard options.
Warning though, my function is not terribly efficient. It's performance may not be great with trees this big, so expect it to be a little sluggish.