A dict.cn example sentence for 热烈 is:
tā yīn shòudào rèliè huānyíng ér gāoxìng
He was pleased by the warmth of his welcome.
The translation is mostly straightforward:
But I don't understand what these two are doing in the sentence:
Question: What are 因 and 而 doing in the sentence 他因受到热烈欢迎而高兴?
I would probably phrase it like 他很高兴因为他受到热烈的欢迎.