What does "合う" mean when used with "味" here?
Is this just the same as "味わう"?
味合わない is just a common misspelling of 味わわない. Since 味わう is a regular consonant-stem verb, its nai-form is あじわわない and its causative-form is あじわわせる.
However, some people type or pronounce it as あじあわない or あじあわせる instead, and IMEs that don't recognize this wrong spelling may convert it to 味合わない or 味合わせる. My IME cleverly converted あじあわない to アジア和内, which is obviously wrong to everyone, but 味合わない might be unnoticed by some.
As NHK's articles points out, this confusion doesn't happen for 祝う. I have never seen someone conjugate いわう to いあわない or いあわせる. I guess some kind of back-formation may be happening for 味わう; unlike 祝う, 味わう can be analyzed as あじ + わう, and therefore 味合わない might sound somehow logical.