Sounds like you got something wrong when doing the 'GRANT' for 'moodleuser' in your mysql database (or you didn't do it at all).
Installing and upgrading help
Error Message while creating a database
ການສົນທະນາຖືກລັອກ ດັ່ງນັ້ນ ທ່ານບໍ່ມາສາດຕອບກັບມັນ.