"Please fill out the forms in accordance with the instructions from the other day."
"Please~" 「〜てください」
"fill out the forms" 「書類に入力する」 "fill in the forms" も同じ意味です。
"in accordance with~" 「〜に沿って」
"instructions" 「案内」
instructions from the other day" 「先日の案内」
Please fill out the form following the instructions we sent the other day.
Please fill out the form following the instructions we sent the other day.
Please complete the document based on the guidance we shared earlier.
Please enter the information in the document as per our previous 안내. (as per our previous instructions.)
Please input the required details in the form in line with the previous instructions.
「先日の案内に沿って」は、英語だとよく
following the instructions / based on the guidance / as per the instructions
のどれかで言います。
オーストラリア 
アメリカ合衆国 
