Usage of linking words
Is the following sentence correct? Can I use both linking words separated only with a comma?
Additionally, although the quality is...
Solution 1:
One way we can understand your question is by examining "the writer's purpose":
"Additionally, although the quality is..."
Part 1: "Additionally" and "although" are linking/transitional adverbs as you have stated. See link for more of other kinds of transitions- https://writing.wisc.edu/Handbook/Transitions.html.
Part 2: The writer's purpose of using "Additionally" here is to link or transition from the idea before this phrase to the idea presented in this phrase.
For instance: "I did not care too much about buying laptops. My friends did. They suggested that I buy a low-cost but highly reliable laptop. I thought about their suggestions and considered the following points. If I buy the Macbook, I could actually get a college student discount to lower the cost of purchase. Additionally, although the quality..."
You can see that the purpose of using "Additionally" here is to link to the idea before the idea with the word "additionally".
Part 3: The writer's purpose of using "although" here is to qualify/make distinct the idea about "the quality" from another subject of comparison or contrast. For instance: "although the quality of the Macbook was not as good as the quality of the HP laptop...".
Hope this helps a little.
Someone else can say something about the function of these linking adverbs too if they want.
Blessings Peter