“Someone should let New Advent know:”
Why? As far as I can see nowhere in what you quoted did it say the Church ever authorized the sale indulgences.
“Can you please provide the letter with the alleged order not to sell indulgences?”
If you mean Albrecht’s letter of instruction, look it up. I listed the source which shows no sale was possible if everyone simply followed the instructions.
“And why would Leo offer it in the first place and then declare that he will keep one half the returns, if the selling of indulgences was refused?”
Your question makes no sense. The fact that there was no selling of indulgences doesn’t mean that people did not follow the instructions and donate if they were able. Those who could not donate anything still received the indulgence (that is, the certificate) like anyone else. That also shows there were no sales intended.
“And why would Albrecth, in his zeal, simply want to give money to the Pope which he gained through selling indulgences?”
Albrecht never intended for money to be made by the selling of indulgences in the first place. Donations were to be collected. A portion was to be sent to Pope Leo - who had granted the right to the preaching of the indulgence. Neither Pope Leo nor Archbishop Albrecht authorized any sale of indulgences.
“Why? As far as I can see nowhere in what you quoted did it say the Church ever authorized the sale indulgences.”
Read it again:
“Various doubtful and reprehensible methods were resorted to for raising money. He created new offices and dignities, and the most exalted places were put up for sale. Jubilees and indulgences were degraded almost entirely into financial transactions”
And, further:
“To indemnify hiim, and to make it possible to discharge these obligations Rome permitted him to have preached in his territory the plenary indulgence promised all those who contributed to the new St. Peter’s”
The purpose of preaching the plenatry indulgence was for the purpose of “[making it possible to discharge these obligations” which further was “promised [to] all those who contributed to the new St. Peter’s”.
“If you mean Albrecht’s letter of instruction, look it up.”
You referenced a book, which is not available for free online. I then googled Albrecth + letter of instruction, and then tried tying it to Pope Leo, and only found an article talking about a rhinoceros that someone named Albrecht gave as a gift to Pope Leo X.