This is not really an economic terminology. Many words can have multiple meaning in common English. According to the Oxford dictionary:
structure /ˈstrʌktʃə /
1 the arrangement of and relations between the parts or elements of something complex.
2 a building or other object constructed from several parts.
In case of that article the first meaning of the word is used instead of second one.
To be more specific, the authors Hemous and Olsen (2018) use that sentence when they talk about production process and production function of the company so what they mean is the that the capital can be used in the meaning 1 that is used in the arrangement of and relations between the parts of the production.