What do you usually need when you check in at a hotel?
怜奈先生のおっしゃるように to check in...（チェックインするために）
という言い方もできますし、when を使ってもいいですね。
ちょっと一般論として表現してみました。
What do you usually need when you check in at a hotel?
ホテルにチェックインするとき、普通は何が必要ですか？
What will I need to prepare to check in at the hotel?
What are the requirements for checking in to the hotel?
What will I need to provide at check-in?
"What will I need to prepare?" or "What will I need to provide"is a way of asking what you need to do, or what you will need to be ready to give to the staff at check-in.
"What are the requirements?" is a way of asking what is required or what items are required of those checking in.
Check-in is the term for the time or the action of checking into a hotel.
"What will I need to prepare?"（何を用意すればいいですか）と "What will I need to provide?"（何を用意すればいいですか）では、チェックインのときにスタッフに何を渡さないといけないかを尋ねています。
"What are the requirements?"（必要なものは何ですか）では、チェックインのときに必要となるものを尋ねています。
"Check-in"は、ホテルにチェックインする手続きを表します。
"What documentation is needed to check into a hotel?"
In order to make sure you have all the requirements when checking into a foregin hotel, it would best to say "What documentation is needed to check into a hotel?". This outlines that you wish to know what is needed in order for you to have a successful check in.
外国のホテルにチェックインする際に必要となる物を確認したいなら、次のように言うのがベストです。
"What documentation is needed to check into a hotel?"（ホテルにチェックインする時にはどんな書類が必要ですか）
この文では、チェックインする際に何が必要なのか尋ねています。
What documentation is needed for checking in a hotel.
*What documentation is needed for checking in a hotel.- the word documentation includes any documents that will needed for checking in. This will include your ID,invoice for the booking etc.
For example:
A:What documentation is needed for checking in a hotel.
B: They will need only your ID because they will be able to pick the rest of your information in their database.
例文
*What documentation is needed for checking in a hotel.
ホテルにチェックインするのに何の書類が必要ですか？
documentationという語にはチェックインに必要なあらゆる書類が含まれます。身分証明書、予約のインボイス等です。
例文
A:What documentation is needed for checking in a hotel.
ホテルにチェックインするのに何の書類が必要ですか？
B: They will need only your ID because they will be able to pick the rest of your information in their database.
データベースでその他の情報を収集するから、身分証明書だけが必要だ
What do I need to prepare when I'm checking in at a hotel?
What documents do I need to check into a hotel?
What do I need to provide to check in to this hotel?
When going to a hotel to stay you usually have to provide/show documents such as your passport for security and to check you into the hotel
To provide means to give something or to show them something
Documents would be a visa/ID/passport etc
To check in means to sign paperwork to get your room
Which documents do I need when I check in at the hotel?
What documentation is required when checking into a hotel?
When talking about staying at hotels abroad, and you want to ask someone what you need to prepare when you want to check in at a hotel (such as an ID etc), then you may apply one of the above exampled sentences.
What will the hotel need to check when I check in?
What are the requirements needed to check in to this hotel?
easy and casual ways of asking what the hotel will need in order to 'check in'.
'Check' is used to describe to see or observe something ex. passport/ID and reservations.
'Requirements' are used when describing thing that will be used/needed to complete something, in this case to check in to the hotel.
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