QLog uses the external TQSL utility to upload to LoTW. QLog itself does not need any password to upload ADI to LoWT. If you are asked to enter a password then it is requested by TQSL because TQSL has to unlock your private key to sign the ADIF File. Private Key password? is not a Login password. Both passwords can be the same or different. it's up to your preferences how you set it up.
On the other hand, the download is managed by QLog.Here QLog uses the password entered in QLog's settings.I tested several password options that contain special characters such as /," which could cause problems in HTTPs communication, but I did not notice any problems. This password has to be the same as you are?using during authorization to the LoTW site.
Please, verify whether the QLog Setting ->LoTW tab really contains the correct pair username/password that is used for logging in the LoTW. It is not a password for the unlocking private key of TQSL.
Maybe you can also try the option of temporarily changing the login password to "simpler", which only contains one group of characters, and see if the login is successful.
